Question

Sequences and series

Answer 1

D

Explanation:

`a_(n)=((n+3)!)/((n+3)=((n+3)(n+2)!)/(n+3)=(n+2)!\\a_(1)=(1+2)!=3!=3*2*1=6\\a_(2)=(2+2)!=4!=4*3*2*1=24\\a_(3)=(3+2)=5!=5*4!=5*24=120\\a_(4)=(4=2)!=6!=6*5!=120*6=720\\a_(5)=(5+2)=7!=7*6!=720*7=5040`